1. Field of the Invention
This invention relates to a leg extension system for wheelchairs and, more specifically, to an internally contained leg extension system.
2. Description of the Prior Art
It is known in the art to provide either a powered or manual articulating leg rest for a wheelchair. An example of such a device is described in U.S. Pat. No. 5,556,157 to Wempe. Wempe describes a powered system that articulates a pair of leg rests.
One of the problems associated with prior art leg extension systems is the external placement of linkages used to extend and retract the wheelchair legs. Exposure of these linkages can lead to damage or premature wear if external elements come into contact with the linkages. More importantly, such external linkages can lead to personal injury, if a digit or limb is unintentionally exposed to the linkages as they are extended or retracted.
Another problem associated with prior art systems is the coupling of the extension system to a chair back tilt apparatus. While such a combination is often advantageous, in many situations the operator desires to operate the extension system independently of the tilting of the chair back. The linkages in such prior art systems prevent such independent operation.
For the foregoing reasons, it would be desirable to provide an articulated leg extension system for a wheelchair with internally contained extension and retraction means to shield the system from damage, to allow independent operation of the extension system and to prevent personal injury from exposure to external linkages. The difficulties encountered in the prior art discussed hereinabove are substantially eliminated by the present invention.
In an advantage provided by this invention, a wheelchair leg extension and retraction system is provided which shields the extension and retraction assembly from damage;
Advantageously, this invention provides shielding of a wheelchair""s leg extension retraction system from contact with a user to reduce the occurrence of personal injury;
Advantageously, this invention provides a wheelchair leg extension and retraction system which reduces mechanical clutter on the wheelchair;
Advantageously, this invention provides a wheelchair""s leg extension retraction system to operate independently of the chair back tilt mechanism;
Advantageously, this invention provides a self-contained leg extension and retraction system for a wheelchair which can be adapted to provide a shock absorption means for prevention of damage to the system;
Advantageously, in a preferred example of this invention, an improved wheelchair leg rest extension apparatus is provided, comprising a frame and an extensible member received by the frame. A leg rest is operably coupled to the extensible member and means are coupled to the extensible member for extending and retracting the extensible member. Means are also provided within the frame, and operably coupled to the extensible member, for moving the extensible member relative to the frame.
In the preferred embodiment, the extensible member is a screw and sleeve, received by a frame tube of the frame. Means are provided for rotating the screw in a manner which extends the sleeve and rotates the leg rest into an extension or retraction position in response thereto.